Wireless broadcast service has gained popularity as one of the most typical mobile communication services. The mobile broadcast service may be unicasted from a broadcast server to a subscriber through 1-to-1 communication, or may be multicasted/broadcasted from a broadcast server to a number of subscribers through 1-to-N communication.
When compared to a wired communication service, a mobile communication service allows only a small amount of resources to be allocated among subscribers, and thus a communication fee is much more expensive than the wired communication service. Hence, it may be desirable for a mobile communication system to employ a multicast/broadcast service (MBS) that enables to deliver the same broadcast content to many users in parallel by use of one resource.
To this end, standardization specifications, such as IEEE802.16e, IEEE802.16m, 3GPP/LTE and Worldwide Interoperability for Microwave Access (WiMAX) forum, suggest an MBS which is named an Enhanced-MBS (E-MBS), a Multicast Broadcast Multimedia Service (MBMS), an Enhanced-MBMS (E-MBMS), or a MultiCast BroadCast Service (MCBCS) in a single-frequency network environment.
According to MBS specifications provided by IEEE802.16e or IEEE802.16m, a plurality of base-stations are included in one broadcast service area and all base-stations in the same broadcast service area deliver broadcast content to terminals using the same wireless resource. IEEE802.16e or IEEE802.16m defines this MBS broadcast area as an MBS zone or an E-MBS zone. FIG. 1 illustrates an example of MBS zones specified by IEEE 802.16e or IEEE802.16m.
For the implementation of MBS, all users within the same cell should be able to receive service data. Thus, a base-station that delivers the MBS needs to generate an MBS data signal by taking into consideration users' locations, for example, a boundary of each cell, where the proper reception of the MBS data signal is difficult. Accordingly, it may not be possible to provide the MBS at a service quality as provided by a unicast service. However, to overcome these drawbacks, the standardization specifications define enhancement of an MBS reception quality by use of macro-diversity. The effects of macro-diversity increase as more adjacent base-stations are transmitting the same signal.
As discussed above, it may be understood that it is difficult to create an MBS zone that completely meet a service request by a user that is moving in a fixed MBS environment. Especially, in a fixed MBS environment, wireless resources for the MBS are always needed to be allocated to access nodes or base-stations, which are not connected to MBS users, and this significantly wastes the wireless resources. Further, a single base-station (BS) MBS specified by IEEE 802.16e forms an MBS zone by a single base-station and thus can use wireless resources most efficiently, but cannot obtain macro-diversity effects so that a quality of the MBS is deteriorated. Hence, there arises a need for a new method to enhance a quality of MBS while reducing an amount of wireless resources used by a base-station for the provision of the MBS.